Stress and structure of silicon surfaces

Abstract

It is well-known that a surface's structure affects its properties; the effect of a surface's intrinsic stress, however, is less widely known but just as important. Using the novel technique of ultra-high vacuum transmission electron microscopy, I have investigated both the structure and the stress of the Silicon (111) surface. The kinematic analysis of electron diffraction data was used to determine the positions of the surface atoms of the Si(111)-7x7 reconstruction. Even under the seemingly drastic kinematic approximation, the atomic positions determined were in excellent agreement with those determined by x-ray diffraction. The relation of stress to structure is revealed in the 7x7 to "1x1" phase transition on the Si(111) surface. While only a small amount of stress is relieved in the transition, it is clearly measurable, with a value of 30meV/A$\sp2$. This value is consistent with the disordered adatom model for "1x1" surface.